


Ocean Blue

by Sorkari



Category: Shingeki no Kyojin | Attack on Titan
Genre: Alternate Universe, Eventual Smut, M/M, Merperson Levi (Shingeki no Kyojin), Mild Gore, Nonbinary Hange Zoë, Strangers to Lovers
Language: English
Status: In-Progress
Published: 2018-03-08
Updated: 2018-03-28
Packaged: 2019-03-28 12:28:36
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 3,902
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13904034
Author URL: https://archiveofourown.org/users/Sorkari/pseuds/Sorkari
Summary: Erwin didn't believe in myths. Not until he found one hiding under the pier.





	1. Chapter 1

**Author's Note:**

  * For [CaptainReina](https://archiveofourown.org/users/CaptainReina/gifts).



> For some reason, I wrote a mermaid (merman?) AU for my future spouse because I love them and therefore must write 20 different stories for them. I like making them happy. It's the single most fulfilling thing I can ever do.
> 
> I'm gonna throw a bone and say this takes place in 18th century Portsmouth, New Hampshire.

In the middle of the night, on a beach that was only scarcely graced with the light of the moon, it wasn't uncommon to hear strange things coming from the ocean. It also wasn't uncommon for a guard to slack off and wander away from his post, most commonly to wander over to a nearby pub. What made both things uncommon was when they intertwined. What made it even more uncommon was when it wasn't a common guardsman, but the captain himself.

The first few times captain Dok took the night shift for himself under the premise that there was "unruly behavior" reported through several eyewitness accounts, no one said a thing. Keep quiet, the public must not know, the captain is fully capable of handling an issue that most likely resulted from the restless whalers that recently returned home after a four year voyage. Except after the first several days, it became suspicious, and on the fifth day when he didn't return from his post at midnight for the next guardsman to take over, it became alarming.

The very first thing that Erwin was able to confidently confirm with both himself and any outside parties was that he did not believe in myths.

They're _myths_. Stories used to scare small children. That's all there was to them.

So naturally, as a skeptic, when he reached the docks that night with Hange yipping away at his heels, he didn't think twice of the mist that lingered over the sand. The ocean yawned, smoothing delicately over the soft, glittering surface of the wet sand, then pulled away with an equally delicate gasp. Being so close to the ocean, he could feel the chill of its foamy breaths sink through the layers of hemp that typically shielded him from the cold when he patrolled the town's streets.

At the very first chill that raked down his spine, Hange abruptly stopped in the middle of their sentence with a heavy sigh, a puffy cotton-like cloud rushing out between their lips. "I'll check the alleyways!" Hange stated, finality evident in their tone. Then, less sternly, they whispered, "How much you wanna bet that he's _drunk_?"

Erwin pursed his lips, not pleased with having to come nearer to the ocean, but not quite upset enough to protest. At Hange's large, impossibly bright smile, he offered, "Ten shillings."

It was small, almost insignificant, but it was enough to satisfy them. Hange left him at the beginnings of the beach, where sand mingled with dirt and stone, their conjoined lamplight dwindling and leaving Erwin in a small flickering bubble that illuminated just a few feet ahead of him. Their footsteps slowly suffocated and died, leaving him alone with the abyss that reached out towards him, climbing up the beach far enough to throw salt in his nose before it receded with a loud, spiteful hiss.

The ominous beauty of the ocean fascinated him; there were things people never thought twice about, not until they were given the chance to appreciate it in another light. Or lack of one - the clouds overhead slowly inched towards the moon, and the glow of white and silver against the ocean vanished. Erwin held the lamp out further ahead of him, until he came close to the pillars of wood that marked the mouth of the nearest pier. The pier was empty, or at least appeared to be empty, and with the limited view, there wasn't much he could do.

By the time he had reached the end of the pier and returned to the mouth of it, the clouds had steadily unveiled the moon, allowing her to shine brightly upon the beach again. With this, his field of vision grew, and accordingly, a glint in the corner of his eye caught his attention. At the foot of one pillar, a bolo tie lay at the very edge of the wood, the strings flowing off the edge as if reaching out below. It glowed a deep red, bold and brash and blatant; it screamed of Nile.

Erwin stepped near the edge of sand where bright orange sandstone started, the jagged, uneven rocks leading down into a pit below the pier. He crouched down, stepping carefully over the slippery rocks, and he progressed halfway down the hill before he slipped. He didn't fall, but he did drop his lantern, the sharp, metallic ringing of it echoing loudly in his ears as it bounced down against the rocks and finally hushed as it slid along the sand below and rolled into the water. He followed after it as he regained his balance, more careful on the last few feet of his descent, and picked up his lantern. The lamplight was gone, but he didn't need any extra light besides the moonlight to glance below the pier.

Half hidden by the shadow of the pier, but still illuminated by the moon, a pair of narrowed silver eyes stared directly at him. Erwin wasn't quite sure whether he dropped his lantern again or not, his mind hyper focused on those irresistibly bright eyes. All thought gradually vanished, washing away with the ocean as it reached up to lap at his ankles, then crawled back into the abyss with a gentle murmur.

One slender hand slowly reached up to the sharp, beautifully unmarred face that belonged to those tantalizing eyes and wiped at the thin lips that curled ever so slightly into a coquettish smile. It pulled away with a smear of scarlet across the skin. Erwin regained some sense of control, his chest fluttering, the fleeting weight in it painfully apparent as if he had forgotten how to breathe for a few seconds. The smile on the man faded, sharp eyes never once blinking, never moving, poised on him with an ominously inscrutable expression.

The man before him straightened, slowly, deliberately, revealing the body that he had been crouched over moments prior, similar to a predator caging in its prey. The whispers of the ocean crept out of the corners of Erwin's mind and allowed him to process that, beneath the thin, pallid man lay a body, nearly unrecognizable now. It was littered with teeth marks, the jagged edges of ripped skin and the ruined fabric of an unmistakable uniform sticking together until it nearly became one.

With a deep, honeyed voice, the man hummed softly, "Yes, sir?"

He was upright now, both arms holding him up, his shoulders cradling his head in an innocent manner. Crimson covered his forearms and smeared against his abdomen, a stark contrast to the ethereal white of his smooth, unmarred skin. Were it not for that, Erwin would have followed the unmistakable pull forward, a calling that made him yearn for more. Instead, he squared his shoulders, now conscious of the heavy rise and fall of his chest, and the man's considerable lack of one.

Trailing even lower, framing the perfect dip of his hips to his groin, a horizon of light green emerged on his skin in a gradient, merging to an exquisite teal as it trailed lower and then, finally, deepening to a strong blue, as bold and bright as the ocean. The fin, thin and curved at the base into an elegant cupid's bow in a thick line of ocean blue, lay just a few feet away from Erwin's left, flicking in the water. The man didn't dare move, and justly, neither did he, not even as the ocean returned again to envelop his ankles in its agonizingly cold embrace.

The man's croon resonated in Erwin's chest, a sound more fascinating than any song he had ever heard before; "Come here."

It was hard not to take a step forward. His body screamed for such, chest ached for it, mind swarm in desperate circles in an urgency to respond to the voice that called for him. There was nothing demure about his demeanor any longer; he narrowed his eyes, a pointed tongue darting out to lick his thin lips, and damn it all, Erwin followed it with a shallow sigh. It was enough to encourage the man to try again.

"What's wrong?" Petulantly, the man pouted, reaching forward again, slowly lowering himself into a predatory crouch as he pleaded with a silvery voice, " _Come here._ I'm so _lonely._ "

It almost felt _wrong_ , to stand there against the tide, to refuse to let himself fall into the easy flow of it. Maybe he would have, if those mesmerizing eyes hadn't left his, if the glower of molten silver had stayed on him any longer than it did.

"Erwin?"

Hange's voice was heard a considerable distance away, but it was no doubt getting closer, following the hastened thudding of boots along the sand. Erwin realized, now, that he had begun to step forward, had already been on his heel to give the man what he wanted. The chill sunk through his coat and into his skin, wracking shivers down his spine, and backing away was now an achievable feat.

Erwin watched the carefully constructed insouciance fall from the creature's face as he called back, "I'm here."

Hange finally reached him, calling down from above, "What happened? Did you find something down there?"

That small, pallid face, still so tantalizingly ethereal, still so smooth in a way that begged for one's touch, contorted into a grimace. He was angry, no doubt, and some part of the charm that had swayed him and kept him locked in place for so long elicited a brief pull of guilt in his chest. The man before him, crouched low over the mutilated corpse, readied to strike, tail receding, lip pulling back with the furious furrow of his brow, the beginnings of pointed teeth starting to emerge -

"Nothing." The man stilled, face falling, eyes widening as if genuinely surprised by the response. Erwin repeated firmly, fully by his own accord, "Nothing. I dropped my lamp."

He heard the crunch of boots against the rocks, pebbles falling from above. "Well, hurry up and grab it. It's cold down here."

Erwin knew, with a painful regret, that he needed to go. The ocean retreated back into itself, leaving a glittering sheen on the man's lustrous tail. His scales glowed a baby blue, similar to the ones that had gathered around his forearms, now clean and pure after the water had enveloped them many times, more often than Erwin had realized. There was nothing more beautiful than the way his tail, with tips whiter than any shining pearl, reached up to curl around him, curving protectively around a slender shoulder. It was diminutive, defensive, but not enough to be considered submissive. Erwin assumed that this was the man's way of giving him permission to leave.

He found Hange waiting impatiently for him, rubbing their hands together furiously in a futile effort to stay warm. Hange shakily murmured something about never returning so late at night, when the world seemed to freeze over, but Erwin didn't complain. He didn't need to.

There was nothing that could keep him from coming back.


	2. Chapter 2

**Notes for the Chapter:**

> hi friends ill proof read this after i take a nap

The death of the captain of the guard sparked a small anarchy that was hard to keep quiet in such a tight-knit community. In the midst of confusion, there were no guards that would willingly take their post near the docks, so naturally, Erwin volunteered to take their shifts. No one protested against this; up on the drawing board, where stations were plotted out, Erwin's name stood prominent at the docks.

He was with Hange when he saw this, and something in him jumped as if shocked. It wasn't fear that coiled in his belly, but a sort of quiet ecstasy that sent chills down his spine. There wasn't anything to say, not until Hange wistfully sighed, "Captain Dok was found under that pier."

If Erwin didn't know Hange, he wouldn't have recognized the accusation. It didn't surprise Erwin that they made this observation, and it was equally as uneventful that they didn't speak a word of it to anyone else. But now the two were alone, late in the evening when most had gone home, and without a captain, the station was vacant, eery, quieter than the town in the dead of night. Erwin glanced at them, meticulous in the way he schooled his countenance, hopefully inscrutable enough to deter any suspicion.

He responded in his usual calm, smooth hum, "Funny coincidence, isn't it?"

 _"_ Funny," Hange repeated, lip pulled back in a grimace as if they had bitten down on tin. "I guess it would be, if I didn't feel responsible." Erwin looked away, back up at the board where his name lay pinned to the parchment. They pressed a bit too harshly, "I don't know - don't  _you_ , Erwin?"

In his mind, where a strong, shining ocean blue was the only thing he could focus on, he could still hear the nearly imperceptible murmur of the ocean, could still see the way the man's irises flowed with molten silver as naturally as his fin flowed in the water. He bit his lip, unable to deny the tugging in his chest that called him to the docks.

"I do," Erwin answered, conscious enough to add a grimness to his voice when he offered as a fake admission, "so I'm going back." Glancing back at Hange, he could see that it was sufficient. A weight lifted from his shoulders now that he didn't have to concern himself with troublesome things like suspicions. Pale, thin lips curled into an irresistible smile, and he added with a murmur, "Until I find the suspect."

"Oh?" Hange folded their arms over their chest. "Well, I wanted to tell you something. A secret. Can I trust you?"

"If you can't even keep your own secret, why do you expect me to?"

"Don't be an ass," Hange laughed. The lighthearted nature of the exchange died, however, when they quietly stated, "I saw something before you left that night. One little thing." The hushed whispers of the sea melted away, receding permanently into the abyss, and Erwin met Hange's eye, narrowed and alarmingly enigmatic. "I don't know what it is, exactly, but you're going back to it."

There were no explanations that Erwin could grasp for, at least none that he was capable of forming at the moment. The only thing he could possibly offer was; "If not me, then who else?"

After one laborious moment, a smile cracked through the serious demeanor, and Hange punched him on the shoulder. "You're one crazy son of a bitch, Erwin Smith." They glanced down the hallway behind them when they heard footsteps, then leaned in towards Erwin to whisper, "This doesn't feel right. None of this does. I don't know what you're doing, but I trust you, and I don't even know if that's a good idea at this point." Pulling away, they added excitedly, "And if you don't tell me anything about it, we're not friends anymore. Okay?"

Erwin smiled. "I wouldn't have it any other way."

* * *

For the first few nights, Erwin found nothing.

Murmurs of the former captain's fate started to die down, but the tension remained. Rumors had it that Erwin was to be the next captain, and if they were true, tomorrow would be the his final night patrolling near the beach at night. He was at a loss a this point. It was a tension that kept him standing his post as alert as he did, strewn taut as if one tiny jolt would break it.

That night was particularly cold, with occasional winds that rattled through his uniform and into his bones. It came from the ocean, and each time it reached out to him, whispering encouragingly to come along, he could only stare helplessly. Some part of him hoped to see the unmistakable glisten of scales just beneath the surface of the water.

At some point, he had entered a sort of trance that was neither conscious nor unconscious, and was only snapped out of it at the faint splash of water. When the ocean receded, it was quieter than normal, taking a breath before continuing to whisper to him as it stretched out along the sand. Again, the ocean quieted, and there was another splash, almost imperceptible but still undeniable. Despite the growing chill, he wandered closer to it.

There was a dip in the sand of the nearest pier, creating a hill, curving down below the pier. Within that comfortable pocket of sand beneath the pier, cushioned by a tail, fin waving lazily in the water, sat a tantalizingly pale man.

The beach hushed, ceased in its whispers as quickly as all the thoughts in Erwin's mind had vanished. Talking was too laborious of a task; instead he waited, watched as a hand, unmarred and so delicately slender, reached up to brush silky raven locks out of his eyes.

"They don't always come back."

A few moments passed, an unspoken invitation, and Erwin took it as permission to sit down. He sat at the peak of the hill, his heart aching for him to go closer, his mind pleading to sit next to the man in the large space beside him. Instead, he averted the urge with an inquiry; "They?"

Finally, as if a burden had been lifted from his shoulders and allowed him to breathe again, the man looked up at him. "Tell me - what keeps you here?"

The ocean charged forth, engulfing the man in dark, freezing water. It pooled up to his waist, scratching at the sand before falling back, his tail emerging once more with a sharp glint. He straightened up a bit, breath held tight. Under the moonlight, a faint glow radiated from the man's skin. Everything was delicate, from his silken hair to the beautiful arch in his tail, curved upwards towards his chest as if propping a knee up.

"I want to know why."

It was the first and only thought in Erwin's mind, one that seemed to take the man by surprise. For awhile, there was nothing, and even as Erwin started to shiver and his teeth threatened to chatter, he refused to leave. The mild suffering was worth it, of course, when he heard the man say, "I thought it wasn't all bad out here."

Water flooded the dip once more, this time filling high enough to reach the man's chin. The ocean pulled back with another soft hum, and Erwin could see, with a rush of fascinated wonder, that the dark slits on the sides of the man's throat flexed as they emerged from the water again.

"There was a man once," he continued, voice soft and silvery as if relishing in the nostalgia, "a long time ago, when the Old World was the only world anyone knew." He paused as if waiting for a response, but it never came, and he continued, "A father. A friend to many. A shipbuilder, too, if i remember correctly. I didn't believe in horrible men or women, not yet. But then came the night when he brought me to his friends to play. It was the first time I've ever tasted flesh.  _Human_  flesh," he added with a wistful sigh, "a lovely thing one can never go back on. Not that I'd want to, of course."

His tail smoothed back out onto the sand, the tip falling further into the abyss. Erwin licked his lips, tasting the salt that was there, and for a moment, he wondered if the man before him tasted of it. He shifted in his seat, sand tumbling down into the dip. The memory of the crimson that tainted those delicate hands still burned fresh in his mind. A shiver wracked down his spine, one independent of the chill, but Erwin couldn't pinpoint exactly what it was. He was aware of the nails that curved into a treacherous point on each finger, of the sharp edges of teeth that he could briefly see whenever the man spoke, and for a moment, he yearned to see more, to _know_  more.

"Another time, a young woman, more beautiful than the Queen herself, followed me home." His lips pulled back into what could have been a smile, but the bitterness in his tone led Erwin to believe it was a grimace. " _Home_." The word was punctuated with a brief splash in the water. "Not here. Never here. She didn't understand that, though. Refused to let me go, and if I did anyways, she'd tell." His fingers curled against the sand. "I lost my first nail that day. I think it was worth it. No man would ever marry a woman with a face as mutilated as hers."

Erwin had always been familiar with the masquerade. The man spoke in a deadpan, and Erwin not knowing whether it was genuine or a meticulously constructed mask, there was no disgust. There was only the whispers from the sea, flowing slowly in his mind, calm and tranquil in a way he didn't recognize when he was in the town. Here, still so close to home but dangerously far all the same, there was only him and the man before him, two entirely different worlds that collided.

All morals and responsibilities aside, Erwin eventually allowed himself to say, "You did what you had to do."

The man didn't speak for awhile after that. There were no alarms that went off, not when the tension in his shoulders gradually released, and his carefully poised tail had gone back to absentmindedly curling in the water.

"They call you Erwin?"

Erwin was surprised by the abrupt question, but he answered quickly, "Yes. Erwin Smith." He then asked carefully, "What do they call you? At home?"

The man licked his lips, his pointed tongue drawing attention, vanishing again between sharp teeth, ones that were larger than Erwin had initially thought. With a soft voice, distorted to Erwin's ears in a high, fluttering pitch, the man answered, "Rivaille." After a short pause, he said with the common tongue that wasn't incoherent, "I don't think you could say it, though."

He looked up at Erwin with a glittering wonder in his silver eyes when he attempted it. His voice was too deep and vulgar, tongue refusing to curve in such an intricate way. He clumsily started to settle, "Ri - Reev - Liv -ai.  _Levi."_  Erwin offered gently, "Does 'Levi' sound nice to you?"

The man looked back down at the water that pooled at his waist in contemplation. He tried quietly, "Lee -vi. _Levi._ " He rolled the name on his tongue, pronouncing it with a deep purr than resonated in Erwin's chest. He then concluded, "Okay. I can live with it."

A fluttering sensation was evident in Erwin's stomach, a delighted rush similar to that of ecstasy. "All right, Levi. It's nice to meet you."

When the ocean flooded back in, Levi turned onto his stomach. The sand that stuck to his back washed away as the water crashed over his shoulders, and behind him, protruding from the dark abyss, the thin, pearl white of his fin flicked up and down in subconscious curiosity. Erwin didn't stare, though, didn't even have to force himself to look away from the delicate sight. All he could focus on were those narrow eyes, shining brightly in the moonlight despite the cold, stony mask that had been plastered to his face.

"It's nice to meet you, too."


End file.
